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The efficiency of multiple quantum well (QW) light emitting diodes (LEDs) to a large degree depends on uniformity of hole distribution between the QWs. Typically, transport between the QWs takes place via carrier capture into and thermionic emission out of the QWs. In InGaN/GaN QWs, the thermionic hole transport is hindered by the high quantum confinement and polarization barriers. To overcome this drawback, hole injection through semipolar QWs located at sidewalls of V-defects had been proposed. However, in the case of the V-defect injection, strong lateral emission variations take place. In this work, we explore the nature of these variations and the impact of the V-defects on the emission spectra and carrier dynamics. The study was performed by mapping electroluminescence (EL) and photoluminescence (PL) with a scanning near-field optical microscope in LEDs that contain a deeper well that can only be populated by holes through the V-defects. Applying different excitation schemes (electrical injection and optical excitation in the far- and near-field), we have shown that the EL intensity variations are caused by the lateral nonuniformity of the hole injection. We have also found that, in biased structures, the PL intensity and decay time in the V-defect regions are only moderately lower that in the V-defect-free regions thus showing no evidence of an efficient Shockley-–Read–Hall recombination. In the V-defect regions, the emission spectra experience a red shift and increased broadening, which suggests an increase of the In content and well width in the polar QWs close to the V-defects. [ABSTRACT FROM AUTHOR]

The absorption and photoluminescence (PL) spectra of negatively photodoped ZnO nanocrystals dispersed in ethanol are measured under a stepwise photodoping process at room temperature. The spectra are measured almost simultaneously at each photodoping level and compared in detail to discuss the origin of the spectral change. The redshift of the PL spectrum and the increase of its intensity are clearly observed in the early stage of photodoping and are attributed to the trion luminescence. The PL spectrum is found to split into two peaks for highly photodoped nanocrystals. The cause of the splitting is discussed in terms of its dependence on the nanocrystal size. [ABSTRACT FROM AUTHOR]

Understanding core level shifts in aromatic compounds is crucial for the correct interpretation of x-ray photoelectron spectroscopy (XPS) of polycyclic aromatic hydrocarbons (PAHs), including acenes, as well as of styrenic polymers, which are increasingly relevant for the microelectronic industry, among other applications. The effect of delocalization through π aromatic systems on the stabilization of valence molecular orbitals has been widely investigated in the past. However, little has been reported on the impact on the deeper C1s core energy levels. In this work, we use first-principles calculations at the level of many body perturbation theory to compute the C1s binding energies of several aromatic systems. We report a C1s red shift in PAHs and acenes of increasing size, both in the gas phase and in the molecular crystal. C1s red shifts are also calculated for stacked benzene and naphthalene pairs at decreasing intermolecular distances. A C1s red shift is in addition found between oligomers of poly(p-hydroxystyrene) and polystyrene of increasing length, which we attribute to ring–ring interactions between the side-chains. The predicted shifts are larger than common instrumental errors and could, therefore, be detected in XPS experiments. [ABSTRACT FROM AUTHOR]

We implanted Fe+ ions in nanodiamond (ND) powder containing negatively charged nitrogen-vacancy (NV−) centers and studied their Raman spectra and optically detected magnetic resonance (ODMR) in various applied magnetic fields with green light (532 nm) excitation. In Raman spectra, we observed a blue shift of the NV− peak associated with the conversion of the electronic sp3 configuration to the disordered sp2 one typical for the carbon/graphite structure. In the ODMR spectra, we observed a red shift of the resonance position caused by local heating by an absorptive environment that recovers after annealing. To reveal the red shift mechanism in ODMR, we created a controlled absorptive environment around ND by adding iron-based Fe2O3 and graphitic sp2 powders to the ND suspension. This admixture caused a substantial increase in the observed shift proportional to the applied laser power, corresponding to an increase in the local temperature by 150–180 K. This surprisingly large shift is absent in non-irradiated NV-ND powders, is associated only with the modification of the local temperature by the absorptive environment of NV-NDs, and can be studied using ODMR signals of NV−. [ABSTRACT FROM AUTHOR]

In this work, nitrogen vacancy (NV) centers of high nitrogen diamond implanted with arsenic ions were investigated by photoluminescence spectroscopy. The transition of the NV center charge state was discussed by the regularly changing laser excitation power and measurement temperature following high-temperature annealing. After high-temperature annealing, the amorphous layer generated by arsenic ion implantation is transformed into a graphitization layer, resulting in a decrease in the NV yield. The electric neutral NV (NV0) center and negatively charged NV (NV−) center are affected by both radiation recombination and Auger recombination with increasing laser power. Accompanied by the increasing measurement temperature, the intensities of NV centers gradually decreased and eventually quenched. In addition, the charge states of NV− and NV0 centers were undergoing a transition. The zero phonon line positions of NV centers were also red shift, it was attributed to the dominant role of electron–phonon interaction in the temperature-dependent displacement of diamond energy gaps. The full width at half maxima of NV center were broadened significantly at higher temperatures. [ABSTRACT FROM AUTHOR]

Obtaining accurate lattice thermal conductivity data of LiF under extreme conditions not only provides important reference for performance evaluation, prediction, and control of materials, but also helps to alleviate the significant challenges of precise experimental measurements. The high-temperature phonon properties and lattice thermal conductivity (LTC) of solid LiF were calculated by combining on-the-fly machine learning force fields (MLFFs) with the Green–Kubo method. The introduction of MLFF successfully combines the accuracy of ab initio molecular dynamics with the scalability advantage of classical molecular dynamics. At high temperatures, there is a significant enhancement in the vibrational coupling between the acoustic and optical branches of LiF, as well as resonant effects between Li and F atoms, resulting in strong anharmonicity. Additionally, the main peak of the phonon density of states shows a noticeable redshift compared to the harmonic case. The enhanced coupling of TO and TA modes at high temperature leads to a significant increase in phonon scattering rate. By considering higher-order phonon anharmonicity, the predicted LTC is significantly reduced compared to the results obtained from considering only three-phonon interactions. Along the Hugoniot curve up to 100 GPa (2150 K), the predicted LTC agrees well with the experimental values. These findings demonstrate the crucial role of phonon anharmonicity in promoting phonon scattering. [ABSTRACT FROM AUTHOR]

In this paper, we explore the molecular basis of combining photodynamic therapy (PDT), a light-triggered targeted anticancer therapy, with the traditional chemotherapeutic properties of the well-known cytotoxic agent gemcitabine. A photosensitizer prerequisite is significant absorption of biocompatible light in the visible/near IR range, ideally between 600 and 1000 nm. We use highly accurate multiconfigurational CASSCF/MS-CASPT2/MM and TD-DFT methodologies to determine the absorption properties of a series of gemcitabine derivatives with the goal of red-shifting the UV absorption band toward the visible region and facilitating triplet state population. The choice of the substitutions and, thus, the rational design is based on important biochemical criteria and on derivatives whose synthesis is reported in the literature. The modifications tackled in this paper consist of: (i) substitution of the oxygen atom at O2 position with heavier atoms (O → S and O → Se) to red shift the absorption band and increase the spin–orbit coupling, (ii) addition of a lipophilic chain at the N7 position to enhance transport into cancer cells and slow down gemcitabine metabolism, and (iii) attachment of aromatic systems at C5 position to enhance red shift further. Results indicate that the combination of these three chemical modifications markedly shifts the absorption spectrum toward the 500 nm region and beyond and drastically increases spin–orbit coupling values, two key PDT requirements. The obtained theoretical predictions encourage biological studies to further develop this anticancer approach. [ABSTRACT FROM AUTHOR]

Photofragment spectroscopy is used to measure the vibrational spectra of V 2 + (CH 4) n (n = 1–4), V 3 + (CH 4) n (n = 1–3), and V x + (CH 4) (x = 4–8) in the C–H stretching region (2550–3100 cm−1). Spectra are measured by monitoring loss of CH4. The experimental spectra are compared to simulations at the B3LYP+D3/6-311++G(3df,3pd) level of theory to identify the geometry of the ions. Multi-reference configuration interaction with Davidson correction (MRCI+Q) calculations are also carried out on V 2 + and V 3 + . The methane binding orientation in V 2 + (CH 4) n (n = 1–4) evolves from η3 to η2 as more methane molecules are added. The IR spectra of metal-methane clusters can give information on the structure of metal clusters that may otherwise be hard to obtain from isolated clusters. For example, the V 3 + (CH 4) n (n = 1–3) experimental spectra show an additional peak as the second and third methane molecules are added to V 3 + , which indicates that the metal atoms are not equivalent. The V x + (CH 4) show a larger red shift in the symmetric C–H stretch for larger clusters with x = 5–8 than for the small clusters with x = 2, 3, indicating increased covalency in the interaction of larger vanadium clusters with methane. [ABSTRACT FROM AUTHOR]

We investigate small tantalum clusters Tan+, n = 2–4, for their capability to cleave N2 adsorption spontaneously. We utilize infrared photon dissociation (IR-PD) spectroscopy of isolated and size selected clusters under cryogenic conditions within a buffer gas filled ion trap, and we augment our experiments by quantum chemical simulations (at DFT level). All Tan+ clusters, n = 2–4, seem to cleave N2 efficiently. We confirm and extend a previous study under ambient conditions on Ta2+ cluster [Geng et al., Proc. Natl. Acad. Sci. U. S. A. 115, 11680–11687 (2018)]. Our cryo studies and the concomitant DFT simulations of the tantalum trimer Ta3+ suggest cleavage of the first and activation of the second and third N2 molecule across surmountable barriers and along much-involved multidimensional reaction paths. We unravel the underlying reaction processes and the intermediates involved. The study of the N2 adsorbate complexes of Ta4+ presented here extends our earlier study and previously published spectra from (4,m), m = 1–5 [Fries et al., Phys. Chem. Chem. Phys. 23(19), 11345–11354 (2021)], up to m = 12. We confirm the priory published double activation and nitride formation, succeeded by single side-on N2 coordination. Significant red shifts of IR-PD bands from these side-on coordinated μ2-κN:κN,N N2 ligands correlate with the degree of tilting towards the second coordinating Ta center. All subsequently attaching N2 adsorbates onto Ta4+ coordinate in an end-on fashion, and we find clear evidence for co-existence of end-on coordination isomers. The study of stepwise N2 adsorption revealed adsorption limits m(max) of [Tan(N2)m]+ which increase with n, and kinetic fits revealed significant N2 desorption rates upon higher N2 loads. The enhanced absolute rate constants of the very first adsorbate steps kabs(n,0) of the small Ta3+ and Ta4+ clusters independently suggest dissociative N2 adsorption and likely N2 cleavage into Ta nitrides. [ABSTRACT FROM AUTHOR]

The efficiency of usual AlGaN based deep ultraviolet light-emitting devices is still quite low. The difficulties are basically originated from the fundamental material properties of AlGaN. This work has adopted monolayer-scale (AlN)m/(GaN)n ordered digital alloys (DAs) as alternatives to AlGaN random alloys, m and n are the numbers of monolayers. X-ray diffraction scans have demonstrated clear satellite peaks, verifying good periodicity of AlN/GaN DAs grown by molecular beam epitaxy (MBE), and transmission electron microscopy results have revealed atomically sharp and smooth interfaces and quite precise m:n values agreeing well with designs. The electron densities of Si-doped (AlN)m/(GaN)n DAs with high equivalent Al compositions are significantly higher than those of conventional AlGaN:Si random alloys grown in the same MBE system. Si dopant ionization energies in DAs are only 2–5 meV, much lower than that for usual random alloys. The red shift of the light emission for DAs with thinner AlN barriers has suggested strong coupling between the GaN wells and thus formation of a miniband in a vertical direction. The results have demonstrated the potential of the (AlN)m/(GaN)n DAs as electronically functional alternatives for various device applications. [ABSTRACT FROM AUTHOR]

In the analytical process of spectrophotometry, the prerequisite for accurate qualitative and quantitative analysis is obtaining the intrinsic spectra of the analyte. However, the intrinsic properties of spectra can sometimes be masked by easily overlooked non-intrinsic factors, such as those from measuring instruments, leading to erroneous spectral identification. In this study, we documented an unusual redshift phenomenon in the far ultraviolet spectral region. With a spectrophotometer under the nitrogen atmosphere, we selected 14 representative inorganic anions and investigated their absorption spectral behaviors at different optical pathlengths and concentrations. It was intriguing to observe that the absorption peaks with maximum absorption wavelengths below a watershed wavelength of 200 nm underwent a redshift as pathlength and concentration increased, while those above 200 nm did not exhibit a significant redshift phenomenon. In-depth formula simulations and experimental verifications demonstrated that this peculiar spectral behavior was caused by unavoidable stray light in the spectrophotometer. Some methodological and instrumental recommendations are given in the paper. Our study results may serve as a reminder to carefully identify non-intrinsic phenomena when studying absorption spectra in the far ultraviolet region, and provide guidance on spectral corrections in scientific research and practical applications. [ABSTRACT FROM AUTHOR]

Understanding physical mechanisms relies on the accurate determination of fundamental constants, although inherent limitations in experimental techniques introduce uncertainties into these measurements. This paper explores the uncertainties associated with measuring the fine-structure constant (⁠|$\alpha$|⁠) and the proton-to-electron mass ratio (⁠|$\mu$|⁠) using observed fast radio bursts (FRBs). We select 50 localized FRBs to quantify the effects of varying this fundamental coupling on the relation between dispersion measure and redshift. By leveraging independent measurements of dispersion measures and redshifts of these FRBs, we constrain the uncertainties in |$\alpha$| and |$\mu$| approximately to |$\Delta \alpha /\alpha =1.99\times 10^{-5}$| and |$\Delta \mu /\mu =-1.00\times 10^{-5}$| within the standard |$\Lambda$| CDM cosmological framework. Remarkably, these constraints improve nearly an order-of-magnitude when considering a dynamical dark energy model. This investigation not only yields one of the most stringent constraints on |$\alpha$| and |$\mu$| to date but also emphasizes the criticality of accounting for the energy scale of the system when formulating constraints on fundamental parameters. [ABSTRACT FROM AUTHOR]

Measurements of the mean free path of Lyman-continuum photons in the intergalactic medium during the epoch of reionization can help constrain the nature of the sources as well as sinks of hydrogen-ionizing radiation. A recent approach to this measurement has been to utilize composite spectra of multiple quasars at |$z\sim 6$|⁠ , and infer the mean free path after correcting the spectra for the presence of quasar proximity zones. This has revealed not only a steep drop in the mean free path from |$z=5$| to |$z=6$|⁠ , but also potentially a mild tension with reionization simulations. We critically examine such direct measurements of the mean free path for biases due to quasar environment, incomplete reionization, and quasar proximity zones. Using cosmological radiative transfer simulations of reionization combined with one-dimensional radiative transfer calculations of quasar proximity zones, we find that the bias in the mean free path due to overdensities around quasars is minimal at |$z\sim 6$|⁠. Patchiness of reionization at this redshift also does not affect the measurements significantly. Fitting our model to the data results in a mean free path of |$\lambda _{\mathrm{mfp}}=1.49^{+0.47}_{-0.52}$|  pMpc at |$z=6$|⁠ , which is consistent with the recent measurements in the literature, indicating robustness with respect to the modelling of quasar proximity zones. We also compare various ways in which the mean free path has been defined in simulations before the end of reionization. Overall, our finding is that recent measurements of the mean free path appear to be robust relative to several sources of potential bias. [ABSTRACT FROM AUTHOR]

The composition of gamma-ray burst (GRB) jets remained a mystery until recently. In practice, we usually characterize the magnetization of the GRB jets (σ 0) through the ratio between the Poynting flux and matter (baryonic) flux. With the increasing value of σ 0, magnetic energy gradually takes on a dominant role in the acceleration and energy dissipation of the jet, causing the proportion of thermal component in the prompt-emission spectrum of GRBs to gradually decrease or even be completely suppressed. In this work, we conducted an extensive analysis of the time-resolved spectrum for all Fermi GRBs with known redshift, and we diagnose σ 0 for each time bin by contrasting the thermal and nonthermal radiation components. Our results suggest that most GRB jets should contain a significant magnetic energy component, likely with magnetization factors σ 0 ≥ 10. The value of σ 0 seems to vary significantly within the same GRB. Future studies with more samples, especially those with lower-energy spectral information coverage, will further verify our results. [ABSTRACT FROM AUTHOR]

Adsorption of H2 on a bed of NaBr for the formation of NaBr(H2)n (n = 1–8) aggregates is reported here theoretically. Second-order Moller–Plesset perturbation calculations were carried out using the MP2/aug-cc-pVDZ level for predictions of adsorption energies and Gibbs free energy changes for these aggregates. The NaBr(H2)n aggregates are predicted to steadily increase in H2 saving capacity and energy efficiency as n increases from 1 to 8, relative to free H2 molecules under identical conditions. The low activation energies for H2 desorption from the NaBr(H2)n adducts result in high amounts of H2 molecules desorbed at low temperatures. The vibrational stretching frequencies of H2 (H–H) show a red shift. The Natural Bond Orbital calculations were used to investigate the nature of NaBr···H2 interactions. Furthermore, cooperativity was predicted as a result of the stabilization energy of complexes and is discussed. Finally, electronic properties of the NaBr(H2)n clusters were obtained by the density of states calculation. [ABSTRACT FROM AUTHOR]

Localization of fast radio bursts (FRBs) to arcsecond and subarcsecond precision maximizes their potential as cosmological probes. To that end, FRB detection instruments are deploying triggered complex-voltage capture systems to localize FRBs, identify their host galaxy, and measure a redshift. Here, we report the discovery and localization of two FRBs (20220717A and 20220905A) that were captured by the transient buffer system deployed by the MeerTRAP instrument at the MeerKAT telescope in South Africa. We were able to localize the FRBs to precision of |$\sim$| 1 arcsecond that allowed us to unambiguously identify the host galaxy for FRB 20220717A (posterior probability |$\sim$| 0.97). FRB 20220905A lies in a crowded region of the sky with a tentative identification of a host galaxy but the faintness and the difficulty in obtaining an optical spectrum preclude a conclusive association. The bursts show low linear polarization fractions (10–17 per cent) that conform to the large diversity in the polarization fraction observed in apparently non-repeating FRBs akin to single pulses from neutron stars. We also show that the host galaxy of FRB 20220717A contributes roughly 15 per cent of the total dispersion measure (DM), indicating that it is located in a plasma-rich part of the host galaxy which can explain the large rotation measure. The scattering in FRB 20220717A can be mostly attributed to the host galaxy and the intervening medium and is consistent with what is seen in the wider FRB population. [ABSTRACT FROM AUTHOR]

Using deep imaging from the CANDELS and HFF surveys, we present bulge+disc decompositions with galfitm for |$\sim$| 17 000 galaxies over |$0.2 \le z\le 1.5$|⁠. We use various model parameters to select reliable samples of discs and bulges, and derive their stellar masses using an empirically calibrated relation between mass-to-light ratio and colour. Across our entire redshift range, we show that discs follow stellar mass–size relations that are consistent with those of star-forming galaxies, suggesting that discs primarily evolve via star formation. In contrast, the stellar mass–size relations of bulges are mass-independent. Our novel data set further enables us to separate components into star-forming and quiescent based on their specific star formation rates. We find that both star-forming discs and star-forming bulges lie on stellar mass–size relations that are similar to those of star-forming galaxies, while quiescent discs are typically smaller than star-forming discs and lie on steeper relations, implying distinct evolutionary mechanisms. Similar to quiescent galaxies, quiescent bulges show a flattening in the stellar mass–size relation at |$\sim 10^{10}$|  M |$_\odot$|⁠ , below which they show little mass dependence. However, their best-fitting relations have lower normalizations, indicating that at a given mass, bulges are smaller than quiescent galaxies. Finally, we obtain rest-frame colours for individual components, showing that bulges typically have redder colours than discs, as expected. We visually derive UVJ criteria to separate star-forming and quiescent components and show that this separation agrees well with component colour. HFF bulge+disc decomposition catalogues used for these analyses are publicly released with this paper. [ABSTRACT FROM AUTHOR]

Stimuli‐responsive materials based on π‐conjugated donor‐acceptor systems have great potential for sensing applications in solution and solid state. The photophysical properties of an oligo(p‐phenylenevinylene) series consisting of five push‐pull type molecules were systematically investigated to switch their absorption and emission properties by using trifluoroacetic acid as a specific external analyte. During the trifluoracetic acid sensing, the terminal pyridine units of the molecules undergo the protonation and lead to the broader absorption band at a longer wavelength region owing to the π‐π* characteristics of molecules. Upon exposing solid samples to the trifluoracetic acid vapors, the initial color of solid samples changed from yellow to orange for three‐ring system‐based molecules and brick red to wine red color for five‐ring system‐based molecules with the shifting of emission band to the longer wavelength region. Furthermore, exposing the trifluoracetic acid‐fumed solid samples to triethylamine vapors, the color of the solid samples reverted to their original colors and emission properties. The DFT analysis indicated a decreased energy band gap for the protonated molecules compared to the neutral molecules, suggesting a redshift in both the absorption and emission spectra of the protonated molecules. Thus, all the molecules of an Oligo(p‐phenylenevinylene) series can be utilized effectively for volatile acid detection. [ABSTRACT FROM AUTHOR]

In this work, a novel colorimetric chemosensor (BIAD) containing azo chromophore, 1,5dihydroxynaphthalene, and benzimidazole was synthesized and characterized by using IR, 1H,13C NMR, and mass spectral data, and elemental analysis. The cation recognition studies (including fourteen metal cations) exhibited that the synthesized azo dye can act as a rapid, sensitive, and selective colorimetric chemosensor for detecting Cu2+ ions. The addition of Cu2+ ions to the BIAD solution, changed immediately the solution color from purple to blue‐green, which could be observed by the naked eye. Comparison of the UV/Visible spectra of BIAD and (BIAD+Cu2+) revealed a red shift from 543 nm to 616 nm, which confirms the formation of a complex between Cu2+ cations and BIAD molecules. The result of Job's plot indicated that the stoichiometry binding ratio of BIAD to Cu2+ is 1 : 1. The limit of detection (LOD) was found for BIAD toward Cu2+ ion to be 0.10 μM. Furthermore, the BIAD‐based test paper strips were successfully used for the rapid detection of Cu2+ ions (<1 sec) in the aqueous solution (H2O‐DMSO, 9 : 1). [ABSTRACT FROM AUTHOR]

Herein, we report monomeric and dimeric norbornadiene‐quadricyclane molecular photoswitch systems intended for molecular solar thermal applications. A series of six new norbornadiene derivatives conjugated with benzothiadiazole as the acceptor unit and dithiafulvene as the donor unit were synthesized and fully characterized. The photoswitches were evaluated by experimentally and theoretically measuring optical absorption profiles and thermal conversion of quadricyclane to norbornadiene. Computational insight by density functional theory calculations at the M06‐2X/def2‐SVPD level of theory provided geometries, storage energies, UV‐vis absorption spectra, and HOMO‐LUMO levels that are used to describe the function of the molecular systems. The studied molecules exhibit absorption onset ranging from 416 nm to 595 nm due to a systemic change in their donor‐acceptor character. This approach was advantageous due to the introduction of benzothiadiazole and the dimeric nature of molecular structures. The best‐performing system has a half‐life of 3 days with quantum yields over 50 %. [ABSTRACT FROM AUTHOR]

We adopt a Bayesian X-ray spectral approach to investigate the accretion properties of unobscured (⁠|$20\lt \log (N_{\rm H}/{\rm cm}^{-2}\lt 22$|⁠) and obscured (⁠|$22\lt \log (N_{\rm H}/{\rm cm}^{-2}\lt 24$|⁠) active galactic nuclei (AGNs) to shed light on the orientation versus evolution scenarios for the origin of the obscuring material. For a sample of 3882 X-ray-selected AGN from the Chandra COSMOS Legacy, AEGIS, and CDFS extragalactic surveys, we constrain their stellar masses, |$M_\star$|⁠ , intrinsic X-ray luminosities, |$L_{\rm X}$|⁠ , obscuring column densities, |$N_{\rm H}$|⁠ , and specific accretion rates |$\lambda \propto L_{\rm X}/M_\star$|⁠. By combining these observables within a Bayesian non-parametric approach, we infer, for the first time, the specific accretion rate distribution (SARD) of obscured and unobscured AGN to |$z\approx 3$|⁠ , i.e. the probability of a galaxy with mass |$M_\star$| at redshift z hosting an AGN with column density |$N_{\rm H}$| and specific accretion rate |$\lambda$|⁠. Our findings indicate that (1) both obscured and unobscured SARDs share similar shapes, shifting towards higher accretion rates with redshift, (2) unobscured SARDs exhibit a systematic offset towards higher |$\lambda$| compared to obscured SARD for all redshift intervals, (3) the obscured AGN fraction declines sharply at |$\log \lambda _{\rm break} \sim -2$| for |$z \lt 0.5$|⁠ , but shifts to higher |$\lambda$| values with increasing redshift, (4) the incidence of AGN within the theoretically unstable blow-out region of the |$\lambda -N_{\rm H}$| plane increases with redshift. These observations provide compelling evidence for AGN 'downsizing' and radiation-regulated nuclear-scale obscuration with an increasing host galaxy contribution towards higher redshifts. [ABSTRACT FROM AUTHOR]

A host glass of barium-magnesium-boro-tellurite (BTBi0) was produced and reinforced with 10, 20, 30, and 40 mol% of Bi 2 O 3 (BTBi1, BTBi2, BTBi3, and BTBi4) to enhance its gamma rays shielding efficiency. The structural, optical, and attenuation properties of the produced BTBi glass series were studied. Penetration of Bi 2 O 3 up to 30 mol% into the proposed host network enriches it with non-bridging oxygens (NBO) units, while the glass containing 40 mol% was enriched with bridging oxygens (BOs) units, which arose as a result of the role of the Bi3+ ion in disrupting the borate network, leading to the BO 4 ⇋ BO 3 conversion. The conversion role of Bi 2 O 3 was clearly evident in the behavior of the molar volume, oxygen packing density, and packing density. The results of Raman shift showed the formation of the structural units of the boro-tellurite network and BiO 6 units within the glass network. The compositional changes brought about by Bi 2 O 3 agreed perfectly with the results of the optical properties of the studied glass. The red shift in optical absorption spectra, the reduction in the optical band gap, and the augmentation of Urbach energy up to 30 mol% of Bi 2 O 3 occurred mainly as a result of the formation of NBOs units. In contrast, at 40 mol% of Bi 2 O 3 , the continuation of the red shift, the decrease in the optical band gap, and the increase in the Urbach energy, despite the increase in BOs compared to the NBOs, are attributed to the high polarizability of Bi3+ and the formation of BiO 6 units. The transparency of the glass increased to about 85 % with increasing Bi 2 O 3 up to 30 mol%, but decreased to 70 % at 40 mol%. The ability of the considered glasses to attenuate gamma rays was examined using Phy-X/PSD software. The results showed that the attenuation ability improved significantly with increasing Bi 2 O 3 concentrations, where the required thickness to attenuate gamma rays was reduced by 48.505–77.134 % at 40 mol% of Bi 2 O 3. Based on the high attenuation ability and transparency of the studied BTBi glasses, they can be used as a protective shield against gamma rays in nuclear applications that require visual monitoring. [ABSTRACT FROM AUTHOR]

In this study, we present the synthesis of gold nanoparticles (AuNPs) using a completely green synthesis method without the use of any additional functionalizing agent, except dried turmeric root extract. The significant synthesis parameters were optimized, and the applicability of AuNPs was investigated in areas such as plasmonic and fluorescent sensing of aluminum (Al3⁺) and chromium (Cr3⁺) ions, reduction of 4-nitrophenol (4-NP), and degradation of methylene blue (MB) and methyl orange (MO) dyes. Characterization studies were performed using UV–Vis spectroscopy, TEM, FTIR, and XRD, revealing that the AuNPs predominantly had a spherical morphology and a very small particle size of 8.5 nm, with stability maintained up to 120 days. The developed AuNP-based plasmonic sensors relied on aggregation-induced decreases in absorption, along with a red shift in the spectra. Fluorescence sensing demonstrated a linear increase in intensity with increasing concentrations of Al3⁺ and Cr3⁺, with detection limits of 0.83 and 1.19 nM, respectively. The catalytic activities of AuNPs were tested in reducing 4-NP and degradations of MB and MO dyes (binary system) in tap water and wastewater, with the reactions following pseudo-first-order kinetics. This study highlights the potential of AuNPs synthesized from turmeric roots for various environmental and sensing applications. [ABSTRACT FROM AUTHOR]

Dimeric acceptor (DMA) becomes a promising alternative to small‐molecular and polymeric acceptor‐based organic solar cells (OSCs) due to its well‐defined chemical structure, high batch‐to‐batch reproducibility, and low molecular diffusion properties. However, DMAs usually exhibit blueshifted absorptions, limiting their photon utilization abilities. Herein, multi‐selenophene strategies are adopted to develop redshifted DMAs. From monomer (YSe) to dimers (DYSe‐1 and DYSe‐2), reduced electron reorganization energies and exciton binding energies enable the efficient charge dynamics in the DMAs‐based OSCs. Together with their effective absorption extending to ≈920 nm, DYSe‐1‐ and DYSe‐2‐ based OSCs exhibit outstanding short‐circuit current densities (JSCs) over 27 mA cm−2, which are the best among DMAs. Besides, compared with the YSe‐based device, both DMA‐based devices have higher electroluminescence quantum efficiencies and thus reduce nonradiative recombination loss (ΔE3), contributing to their reduced energy losses. The resultant open‐circuit voltages (VOCs) of DYSe‐1‐ and DYSe‐2‐ based OSCs are ≈0.88 V, which, combining their super JSC values, lead to the promising power conversion efficiencies of 18.56% and 18.22%, respectively. These results are among the best in DMAs‐based OSCs and highlight the great potential of the multi‐selenophene strategy for the development of redshifted DMAs with high performance. [ABSTRACT FROM AUTHOR]

The purpose of this study is to investigate the parametrization form of the deceleration parameter in relation to the redshift z. The parameter is represented by the equation q (z) = q 0 + q 1 z (1 + z) (1 + z) 2 , which offers the desirable quality of allowing the sign to be flipped from a decelerating phase to an accelerating phase. We have investigated the Hubble parameter by evaluating the specified parametric form of q and derived constraints on the related free parameters H 0 , q 0 and q 1 with confidence limits of 1 σ and 2 σ by using the χ 2 -minimization approach. Furthermore, we have constrained the current value of the deceleration parameter q 0 = − 0. 4 5 7 − 0. 0 0 2 3 + 0. 0 0 2 2 and obtained that the current universe is accelerating. We have examined the characteristics of our model by assuming the two distinct forms of f (G) = α G m + 1 and f = α 1 G n + β 1 α 2 G n + β 2 . In addition, we have examined the evolutionary paths of energy density, pressure and EoS parameters in order to deduce the universe's accelerating behavior. In order to verify the feasibility of our cosmological model, we also investigate the behavior of various energy conditions. [ABSTRACT FROM AUTHOR]

To non-destructively and rapidly monitor the chlorophyll content of winter wheat leaves under CO2 microleakage stress, and to establish the quantitative relationship between chlorophyll content and sensitive bands in the winter wheat growing season from 2023 to 2024, the leakage rate was set to 1 L/min, 3 L/min, 5 L/min, and 0 L/min through field experiments. The dimensional reduction was realized, fractional differential processing of a wheat canopy spectrum was carried out, a multiple linear regression (MLR) and partial least squares regression (PLSR) estimation model was constructed using a SPA selection band, and the model's accuracy was evaluated. The optimal model for hyperspectral estimation of wheat SPAD under CO2 microleakage stress was screened. The results show that the spectral curves of winter wheat leaves under CO2 microleakage stress showed a "red shift" of the green peak and a "blue shift" of the red edge. Compared with 1 L/min and 3 L/min, wheat leaves were more affected by CO2 at 5 L/min. Evaluation of the accuracy of the MLR and PLSR models shows that the MLR model is better, where the MLR estimation model based on 1.1, 1.8, 0.4, and 1.7 differential SPAD is the best for leakage rates of 1 L/min, 3 L/min, 5 L/min, and 0 L/min, with validation set R2 of 0.832, 0.760, 0.928, and 0.773, which are 11.528, 14.2, 17.048, and 37.3% higher than the raw spectra, respectively. This method can be used to estimate the chlorophyll content of winter wheat leaves under CO2 trace-leakage stress and to dynamically monitor CO2 trace-leakage stress in crops. [ABSTRACT FROM AUTHOR]

This study investigated the impact of erythritol (ERY) on structural and functional properties of whey protein isolate (WPI). FTIR and CD revealed that WPI underwent structural changes, including formation of β‐folds and random coils, upon interaction with 20 mg/mL ERY. SEM showed increased surface roughness of WPI, indicating enhanced protein exposure. Moreover, binding rate exceeded 85%, accompanied by increased surface hydrophobicity. Fluorescence spectroscopy indicated a red shift in fluorescence of WPI and tyrosine (Tyr) residues, altering polarity of Tyr environment due to ERY coordination. Additionally, ERY presence enhanced the functional properties of WPI, including foaming, freeze–thaw stability, rheology and antioxidant activity. [ABSTRACT FROM AUTHOR]

Mining industries have long relied on cyanidation as the primary method for gold extraction, but this process generates thiocyanates as a problematic byproduct, posing challenges for wastewater treatment and recycling. The stability of thiocyanates makes their reduction or elimination in mining wastewater difficult. In this study, a p-n heterojunction of ZnO and BiOI was created and evaluated for its ability to photodegrade thiocyanate ions under simulated solar conditions. Various analytical techniques revealed a highly porous structure with a sponge-like morphology and agglomeration in the synthesized heterojunction. The compound exhibited crystalline patterns without impurity peaks, a slight red shift in absorbance, and Type IV isotherm adsorption. The synthesized heterostructure achieved the complete destruction of thiocyanate ions in less than 30 min. The investigation of different process parameters indicated that the destruction of the contaminant by the heterostructure was influenced by the initial thiocyanate concentration, which decreased as the thiocyanate concentration increased. The peak photodestruction reaction was observed at pH 7. By applying a pseudo-first-order kinetic model, it was found that increasing the catalyst mass to 15 mg raised the rate constant from 0.188 to 0.420 min−1, while increasing the pH to 10 led to a 3.5-fold reduction. The strong correlation between the observed data and the predicted values of the pseudo-first-order kinetic model was indicated by the observed (R2) values. The findings of this study hold potential significance for mining industries, as it offers a potential solution for eliminating cyanide and thiocyanates from mining wastewater. The elimination of thiocyanate generation in the cyanidation process is crucial for mining companies, making this study valuable for the industry. [ABSTRACT FROM AUTHOR]

Galaxy cluster abundance measurements provide a classic test of cosmology. They are most sensitive to the evolved amplitude of fluctuations, usually expressed as |$S_8 = \sigma _8\sqrt{\Omega _{\rm m}/0.3}$|⁠. Thus, abundance constraints exhibit a strong degeneracy between |$\sigma _8$| and |$\Omega _{\rm m}$|⁠ , as do other similar low-redshift tests such as cosmic shear. The mass distribution in the infall region around galaxy clusters, where material is being accreted from the surrounding field, also exhibits a cosmological dependence, but in this case it is nearly orthogonal to the |$S_8$| direction in the |$\Omega _{\rm m}$| – |$\sigma _8$| plane, making it highly complementary to halo abundance or cosmic shear studies. We explore how weak-lensing measurements of the infall region might be used to complement abundance studies, considering three different tests. The splashback radius is a prominent feature of the infall region; we show that detection of this feature in lensing data from the Euclid survey could independently constrain |$\Omega _{\rm m}$| and |$\sigma _8$| to |$\pm 0.05$|⁠. Another feature, the depletion radius where the bias reaches a minimum, also shows cosmological dependence, though it is challenging to observe in practice. The strongest constraints come from direct measurements of the shear profile in the infall region at 2– |$4\, r_{200{\rm c}}$|⁠. Combining the latter with abundance constraints such as those reported from SRG |$/$| eROSITA should reduce the area of the error contours by an estimated factor of 1.2 using a sample of clusters observed by the UNIONS survey, or a factor of 3 using clusters observed by the Euclid Wide survey over a broader range of redshift. [ABSTRACT FROM AUTHOR]

Constraining the escape fraction of Lyman Continuum (LyC) photons from high-redshift galaxies is crucial to understanding reionization. Recent observations have demonstrated that various characteristics of the Ly |$\, \alpha$| emission line correlate with the inferred LyC escape fraction (⁠|$f_{\rm esc}^{\rm LyC}$|⁠) of low-redshift galaxies. Using a data set of 9600 mock Ly |$\, \alpha$| spectra of star-forming galaxies at |$4.64 \le z \le 6$| from the SPHINX |$^{20}$| cosmological radiation hydrodynamical simulation, we study the physics controlling the escape of Ly |$\, \alpha$| and LyC photons. We find that our mock Ly |$\, \alpha$| observations are representative of high-redshift observations and that typical observational methods tend to overpredict the Ly |$\, \alpha$| escape fraction (⁠|$f_{\rm esc}^{\rm Ly\, \alpha }$|⁠) by as much as 2 dex. We investigate the correlations between |$f_{\rm esc}^{\rm LyC}$| and |$f_{\rm esc}^{\rm Ly\, \alpha }$|⁠ , Ly |$\, \alpha$| equivalent width (⁠|$W_{\lambda }({\rm Ly\, \alpha })$|⁠), peak separation (⁠|$v_{\rm sep}$|⁠), central escape fraction (⁠|$f_{\rm cen}$|⁠), and red peak asymmetry (⁠|$A_f^{\rm red}$|⁠). We find that |$f_{\rm esc}^{\rm Ly\, \alpha }$| and |$f_{\rm cen}$| are good diagnostics for LyC leakage, selecting for galaxies with lower neutral gas densities and less UV attenuation that have recently experienced supernova feedback. In contrast, |$W_{\lambda }({\rm Ly\, \alpha })$| and |$v_{\rm sep}$| are found to be necessary but insufficient diagnostics, while |$A_f^{\rm red}$| carries little information. Finally, we use stacks of Ly |$\, \alpha$|⁠ , H |$\, \alpha$|⁠ , and F150W mock surface brightness profiles to find that galaxies with high |$f_{\rm esc}^{\rm LyC}$| tend to have less extended Ly |$\, \alpha$| and F150W haloes but larger H |$\, \alpha$| haloes than their non-leaking counterparts. This confirms that Ly |$\, \alpha$| spectral profiles and surface brightness morphology can be used to better understand the escape of LyC photons from galaxies during the epoch of reionization. [ABSTRACT FROM AUTHOR]

Upcoming telescopes and surveys will revolutionize our understanding of the Universe by providing unprecedented amounts of observations on extragalactic objects, which will require new tools complementing traditional astronomy methods, in particular machine learning techniques, and above all, deep architectures. In this study, we apply deep learning methods to estimate three essential parameters of galaxy evolution, i.e. redshift, stellar mass, and star formation rate (SFR), from a data set recently analysed and tailored to the Euclid context, containing simulated H -band images and tabulated photometric values. Our approach involved the development of a novel architecture called the FusionNetwork, combining two components suited to the heterogeneous data, ResNet50 for images, and a Multilayer Perceptron (MLP) for tabular data, through an additional MLP providing the overall output. The key achievement of our deep learning approach is the simultaneous estimation of the three quantities, previously estimated separately. Our model outperforms state-of-the-art methods: overall, our best FusionNetwork improves the fraction of correct SFR estimates from ∼70 to ∼80 per cent, while providing comparable results on redshift and stellar mass. [ABSTRACT FROM AUTHOR]

This study investigates the clustering and bias of Luminous Red Galaxies (LRG) in the BOSS-LOWZ, -CMASS, -COMB, and eBOSS samples, using two types of simulated lightcones: (i) high-fidelity lightcones from Uchuu N -body simulation, employing SHAM technique to assign LRG to (sub)haloes, and (ii) 16 000 covariance lightcones from GLAM-Uchuu N -body simulations, including LRG using HOD data from Uchuu. Our results indicate that Uchuu and glam lightcones closely replicate BOSS/eBOSS data, reproducing correlation function and power spectrum across scales from redshifts 0.2 to 1.0, from 2 to |$150 \,h^{-1}\,\mathrm{Mpc}$| in configuration space, from 0.005 to |$0.7\, h\,\mathrm{Mpc}^{-1}$| in Fourier space, and across different LRG stellar masses. Furthermore, comparing with existing MD-Patchy and EZmock BOSS/eBOSS lightcones based on approximate methods, our GLAM-Uchuu lightcones provide more precise clustering estimates. We identify significant deviations from observations within |$20 \,h^{-1}\,\mathrm{Mpc}$| scales in MD-Patchy and EZmock , with our covariance matrices indicating that these methods underestimate errors by between 10 per cent and 60 per cent. Lastly, we explore the impact of cosmology on galaxy clustering. Our findings suggest that, given the current level of uncertainties in BOSS/eBOSS data, distinguishing models with and without massive neutrino effects on large-scale structure (LSS) is challenging. This paper highlights the Uchuu and GLAM-Uchuu simulations' robustness in verifying the accuracy of Planck cosmological parameters, providing a strong foundation for enhancing lightcone construction in future LSS surveys. We also demonstrate that generating thousands of galaxy lightcones is feasible using N -body simulations with adequate mass and force resolution. [ABSTRACT FROM AUTHOR]

Spectra of the highest redshift galaxies taken with JWST are now allowing us to see into the heart of the reionization epoch. Many of these observed galaxies exhibit strong damping wing absorption redward of their Lyman- |$\alpha$| emission. These observations have been used to measure the redshift evolution of the neutral fraction of the intergalactic medium and sizes of ionized bubbles. However, these estimates have been made using a simple analytic model for the intergalactic damping wing. We explore the recent observations with models of inhomogeneous reionization from the Sherwood–Relics simulation suite. We carry out a comparison between the damping wings calculated from the simulations and from the analytic model. We find that although the agreement is good on the red side of the Lyman- |$\alpha$| emission, there is a discrepancy on the blue side due to residual neutral hydrogen present in the simulations, which saturates the intergalactic absorption. For this reason, we find that it is difficult to reproduce the claimed observations of large bubble sizes at |$z \sim 7$|⁠ , which are driven by a detection of transmitted flux blueward of the Lyman- |$\alpha$| emission. We suggest instead that the observations can be explained by a model with smaller ionized bubbles and larger intrinsic Lyman- |$\alpha$| emission from the host galaxy. [ABSTRACT FROM AUTHOR]

Utilizing the well-established radial Tully–Fisher (RTF) relation observed in a 'large' (843) sample of local galaxies, we report the maximum allowed variance in the Hubble parameter, |$H_{0}$|⁠. We estimate the total intrinsic scatter in the magnitude of the RTF relation(s) implementing a cosmological model-independent cosmographic expansion. We find that the maximum allowed local 'radial' variation in our baseline analysis, using four RTF relations in the galaxy sample is |$\Delta H_0/H_0\lesssim 3\ \hbox{per cent}$| at a 95 per cent C.L. significance, which is implied form a constraint of |$\Delta H_0/H_0= 0.54^{+1.32}_{-1.37}\ \hbox{per cent}$| estimated at |$D_{\rm L}\sim 10\, [{\rm Mpc}]$|⁠. Using only one 'best-constrained' radial bin, we report a conservative 95 per cent C.L. limit of |$\Delta H_0/H_0\lesssim 4\ \hbox{per cent}$|⁠. Through our estimate of maximum variation, we propose a novel method to validate several late-time/local modifications put forth to alleviate the |$H_0$| tension. We find that within the range of the current galaxy sample redshift distribution |$10 \, [{\rm Mpc}] \le D_{\rm L}\le 140\, [{\rm Mpc}]$|⁠ , it is highly unlikely to obtain a variation of |$\Delta H_0/H_0\sim 9\ \hbox{per cent}$|⁠ , necessary to alleviate the |$H_0$| -tension. However, we also elaborate on the possible alternative inferences when the innermost radial bin is included in the analysis. Alongside the primary analysis of fitting the individual RTF relations independently, we propose and perform a joint analysis of the RTF relations useful to create a pseudo-standardizable sample of galaxies. We also test for the spatial variation of |$H_0$|⁠ , finding that the current samples' galaxies distributed only in the Southern hemisphere support the null hypothesis of isotropy within the allowed noise levels. [ABSTRACT FROM AUTHOR]

The spin-torsion theory is a gauge theory approach to gravity that expands upon Einstein's general relativity (GR) by incorporating the spin of microparticles. In this study, we further develop the spin-torsion theory to examine spherically symmetric and static gravitational systems that involve free-falling macroscopic particles. We posit that the quantum spin of macroscopic matter becomes noteworthy at cosmic scales. We further assume that the Dirac spinor and Dirac equation adequately capture all essential physical characteristics of the particles and their associated processes. A crucial aspect of our approach involves substituting the constant mass in the Dirac equation with a scale function, allowing us to establish a connection between quantum effects and the scale of gravitational systems. This mechanism ensures that the quantum effect of macroscopic matter is scale-dependent and diminishes locally, a phenomenon not observed in microparticles. For any given matter density distribution, our theory predicts an additional quantum term, the quantum potential energy (QPE), within the mass expression. The QPE induces time dilation and distance contraction, and thus mimics a gravitational well. When applied to cosmology, our theory yields a static cosmological model. The QPE serves as a counterpart to the cosmological constant introduced by Einstein to balance gravity in his static cosmological model. The QPE also offers a plausible explanation for the origin of Hubble redshift (traditionally attributed to the universe's expansion). The predicted luminosity distance–redshift relation aligns remarkably well with SNe Ia data from the cosmological sample of SNe Ia. In the context of galaxies, the QPE functions as the equivalent of dark matter. The predicted circular velocities align well with rotation curve data from the SPARC (Spitzer Photometry and Accurate Rotation Curves database) sample. Importantly, our conclusions in this paper are reached through a conventional approach, with the sole assumption of the quantum effects of macroscopic matter at large scales, without the need for additional modifications or assumptions. [ABSTRACT FROM AUTHOR]

In developing his cosmological model of 1917, de Sitter theoretically predicted the phenomenon of cosmological redshift (the de Sitter effect), which he did long before the discovery of this phenomenon in observations. The de Sitter effect is gravitational by its nature, as it is due to differences between the coordinate systems of the observer and the distant source. However, the relationship between the redshift and distance derived from the de Sitter metric is at odds with observations, since this relationship is nonlinear (quadratic) for small redshifts, while the observed relationship between the same quantities is strictly linear. This paper discusses the possibility that cosmological redshift is gravitational by its nature, as in de Sitter's 1917 model. At the same time, here, as in de Sitter's model, an elliptical space is used, the main characteristic of which is the identification of its antipodal points. But, unlike de Sitter's model, here, in order to ensure strict linear dependence of the redshift on distance, the origin of the reference system is transferred to the observer's antipodal point. The Schwarzschild–de Sitter metric used in this model allows you to estimate the curvature of space from observational data. To achieve this, a theoretical Hubble diagram is built within the framework of the model with the Schwarzschild–de Sitter metric, which is compared with observations from the Pantheon+ catalogue of type Ia supernovae and the Amati catalogue of gamma-ray bursts in the redshift range of 0 < z < 8 . As a result of this comparison, we found that the lower estimate of the radius of curvature of space was quite large: 2.4 × 10 15 Mpc. This means that the observational data indicate a negligible curvature of space. [ABSTRACT FROM AUTHOR]

Λ CDM tensions are by definition model-dependent; one sees anomalies through the prism of Λ CDM. Thus, progress towards tension resolution necessitates checking the consistency of the Λ CDM model to localise missing physics either in redshift or scale. Since the universe is dynamical and redshift is a proxy for time, it is imperative to first perform consistency checks involving redshift, then consistency checks involving scale as the next steps to settle the "systematics versus new physics" debate and foster informed model building. We present a review of the hierarchy of assumptions underlying the Λ CDM cosmological model and comment on whether relaxing them can address the tensions. We focus on the lowest lying fruit of identifying missing physics through the identification of redshift-dependent Λ CDM model fitting parameters. We highlight the recent progress made on S 8 : = σ 8 Ω m / 0.3 tension and elucidate how similar progress can be made on H 0 tension. Our discussions indicate that H 0 tension, equivalently a redshift-dependent H 0 , and a redshift-dependent S 8 imply a problem with the background Λ CDM cosmology. [ABSTRACT FROM AUTHOR]

The In‐based double perovskite halides have been widely studied for promising optical‐electric applications. The halide hexagonal perovskite Cs2LiInCl6 was isolated using solid‐state reactions and investigated using X‐ray diffraction and solid‐state NMR spectra. The material adopts a 12‐layered hexagonal structure (12R) consisting of layered cationic orders driven by the cationic charge difference and has Li+ cations in the terminal site and In3+ in the central site of face‐shared octahedron trimers. Such a cationic ordering pattern is stabilized by electrostatic repulsions between the next‐nearest neighboring cations in the trimers. The LiCl6 octahedron displays large distortion and is confirmed by 7Li SS NMR in the Cs2LiInCl6. The Cs2LiInCl6 material has a direct bandgap of ~4.98 eV. The Cs2LiInCl6: Mn2+ displays redshift luminescence (centered at ~610–622 nm) from the substituted Mn2+ emission in octahedron with larger PLQY (17.8 %–48 %) compared with that of Cs2NaInCl6: Mn2+. The Mn‐doped materials show luminescent concentration quenching and thermal quenching. The composition Cs2Li0.99In0.99Mn0.02Cl6 exhibits the highest PL intensity, a maximum PLQY of 48 %, and high luminescent retention rate of ~86 % below 400 K and is suitable for application for pc‐LED. These findings contribute to our understanding of the chloride perovskites and hold potential for widespread optical applications. [ABSTRACT FROM AUTHOR]

Filter elements based on metamaterial structure are one of the essential schemes for researching the miniaturization of spectral detection systems. The aim of this study is to meet the application requirements of different long-wave infrared signal frequency filtering and improve the detection efficiency of micro-filters. In this paper, a periodic micro-nano-cross-linked hole structure is designed, based on the surface plasmonic polariton resonance effect to realize the extraordinary optical transmission performance of 8 ~ 12 μm long-wave infrared. Based on the surface plasmonic polariton excitation mechanism of periodic micro-nano-structures, the tunable performance of the transmission spectra at five central wavelengths of 8, 9, 10, 11, and 12 μm was achieved by changing the simulation period and the overall period of the model, and the optimal peak transmittance was 88.31% with a half-wave width of 1.31 ± 0.01 μm. The present study summarizes the tuning mode and rule of the micro-nano-cross-linked structure to realize the blue/redshift under the performance of the extraordinary optical transmission, which provides an important reference for the miniaturized structure design of infrared spectral detectors and tunable filtering research and is conducive to the application of broadband filtering spectral chips. [ABSTRACT FROM AUTHOR]

We report on the development and commissioning of a new Q-band receiver for the Nobeyama 45 m telescope, covering 30–50 GHz with a receiver noise temperature of about 15 K. We name it eQ (extended Q-band) receiver. The system noise temperatures for observations are measured to be ∼30 K at 33 GHz and ∼75 K at 45 GHz. The half-power beam-width (HPBW) is around 38 |${^{\prime \prime }}$| at 43 GHz. To enhance the observation capability, we tested the smoothed bandpass calibration technique and demonstrated that the observation time can be significantly reduced compared to the standard position switch technique. The wide-bandwidth capability of this receiver provides precise determination of rest frequencies for molecular transitions with an accuracy of a few kHz through simultaneous observations of multiple transitions. Particularly, we determined the rest frequency of SO (JN = 10–01) to be 30.001542 GHz, along with the rest frequency of CCS (JN = 43–32) being 45.379033 GHz, adopting CCS (JN = 32–21) at 33.751370 GHz as a reference line. The SO profile shows a double peak shape at the Cyanopolyyne Peak (CP) position of the Taurus Molecular Cloud-1 (TMC-1). The SO peaks coincide well with the CCS sub-components located near the outer parts of the TMC-1 filament. We interpret that the gravitational infall of TMC-1 generates shocks which enhance the SO abundance. The TMC-1 map shows that carbon-chain molecules are more abundant in the southern part of the filament, whereas SO is more abundant in the northern part. The eQ's excellent sensitivity allowed us to detect faint CO (J = 1–0) spectra from the high-redshift object at a redshift of 2.442. Our receiver is expected to open new avenues for high-sensitivity molecular line observations in the Q-band. [ABSTRACT FROM AUTHOR]

Cosmological redshift suggests that the Universe expands at an accelerated rate. However, by segmenting cosmic redshift into intervals, the rate at which the intervals change with respect to distance diminishes following an inverse power-law relationship. At high redshifts, the impact of additional redshift increments, and the rate at which these intervals change, become marginal. The vanishing redshift intervals in the vertical asymptote suggests a form of temporal compression, indicating an early Universe characterized by higher frequency of events, id est, an increased pace of time. The elongated redshift intervals in the horizontal asymptote reveal a slower rate of time flow near the present. The temporal compression at high redshifts and elongation at low redshifts suggests that redshift is the imprint of the universal deceleration of time on the spectrum of light, not the result of cosmic expansion. The redshift analysis yields two new metrics to estimate the factor of time distortion between a source of emission and an observer in a non-expanding Universe, both predicting that time flows faster at the emitter's past than it does at the observer's present, by a factor (1+z). [ABSTRACT FROM AUTHOR]

The structure and absorption properties of a series of azobenzene derivatives are investigated using the density functional theoretical methods. The study showed that π → π* transitions of azobenzene undergo red shift after mono- and di- substitutions at para positions. Considering the fact that o-fluoro and o-methoxy derivatives of azobenzene have long living cis isomers, the effect of ortho substitution on the excitation energies is examined. An investigation on the azo-protonation revealed prominent red shift for n → π* and π → π* transitions bringing both absorptions in visible region. The effect of substitution on the cis to trans thermal relaxation is also analysed. [ABSTRACT FROM AUTHOR]

Tuning the color of Au has been a longstanding problem in the luxury industry. Conventional approaches, involving Au alloying, compromise purity and demand distinct alloy compositions for each hue. This study demonstrates a lithography‐free method for generating structural colors on a gold surface by adjusting the thickness of titanium dioxide, a high‐index dielectric. While color tuneability is limited if TiO2 is coated directly on the Au surface, a range of vivid colors can be generated if a 50−100 nm thick AuAl2 underlayer is used. AuAl2, an accepted alloy for purple gold, broadens the color gamut, providing a protective coating without diminishing gold purity. The reflectance dip of the bilayer structure exhibits a significant red shift with increasing thickness of the TiO2 layer, allowing diverse colors by TiO2 insulator tuning. Simulation studies corroborate experimental results, affirming that coating a TiO2 layer on the AuAl2 underlayer yields a wide range of colors. This method, based on thin‐film interference, shows promise for widespread use, offering a broad spectrum of structural colors in an industry striving for diverse Au color representation. [ABSTRACT FROM AUTHOR]

Void size function (VSF) contains the information of the cosmic large-scale structure (LSS), and can be used to derive the properties of dark energy and dark matter. We predict the VSFs measured from the spectroscopic galaxy survey operated by China's Space Survey Telescope (CSST), and study the strength of cosmological constraint. We employ a high-resolution Jiutian simulation to get CSST galaxy mock samples based on an improved semi-analytical model. We identify voids from this galaxy catalogue using the watershed algorithm without assuming a spherical shape, and estimate the VSFs at different redshift bins from |$z=0.5$| to 1.1. We propose a void selection method based on the ellipticity, and assume the void linear underdensity threshold |$\delta _{\rm v}$| in the theoretical model is redshift-dependent and set it as a free parameter in each redshift bin. The Markov Chain Monte Carlo method is adopted to implement the constraints on the cosmological and void parameters. We find that the CSST VSF measurement can constrain the cosmological parameters to a few per cent level. The best-fitting values of |$\delta _{\rm v}$| are ranging from |$\sim -0.4$| to |$-0.1$| as the redshift increases from 0.5 to 1.1, which has a distinct difference from the theoretical calculation with |$\delta _{\rm v}\simeq -2.7$| assuming the spherical evolution and using particles as tracer. Our method can provide a good reference for the void identification and selection in the VSF analysis of the spectroscopic galaxy surveys. [ABSTRACT FROM AUTHOR]

We characterize the evolution of the rest-frame 1500 Å UV luminosity function (UVLF) from AstroSat/UVIT F154W and N242W imaging in the Great Observatories Origins Survey North (GOODS-N) field. With deep FUV observations, we construct the UVLF for galaxies at z |$\lt 0.13$| and subsequently characterize it with a Schechter function fit. The fitted parameters are consistent with previous determinations. With deep NUV observations, we are able to construct the UVLF in seven redshift bins in the range z |$\sim$| 0.4–0.8, with galaxies identified till |$\sim$| 2 mag fainter than previous surveys, owing to the high angular-resolution of UVIT. The fitted Schechter function parameters are obtained for these UVLFs. At z |$\sim$| 0.7–0.8, we also utilize Hubble Space Telescope (HST) F275W observations in the GOODS-N field to construct the UVLF in 2 redshift bins, whose fitted Schechter function parameters are then found to be consistent with that determined from UVIT at z |$\sim$| 0.75. We thus probe the variation of the fitted UVLF parameters over z |$\sim$| 0.8–0.4, a span of |$\sim$| 2.7 Gyr in age. We find that the slope of the Schechter function, |$\alpha$|⁠ , is at its steepest at z |$\sim$| 0.65, implying highest star-formation at this instant with galaxies being relatively more passive before and after this time. We infer that this is a short-lived instance of increased cosmic star-formation in the GOODS-N field even though cosmic star-formation may be winding-down over longer time-span at this redshift range. [ABSTRACT FROM AUTHOR]

One of the most promising probes to complement current standard cosmological surveys is the H  i intensity map, i.e. the distribution of temperature fluctuations in neutral hydrogen. In this paper we present calculations of the two-point function between HI (at redshift |$z\lt 1$|⁠) and lensing convergence (⁠|$\kappa$|⁠). We also construct HI intensity maps from N -body simulations, and measure two-point functions between HI and lensing convergence. HI intensity mapping requires stringent removal of bright foregrounds, including emission from our Galaxy. The removal of large-scale radial modes during this HI foreground removal will reduce the HI-lensing cross-power spectrum signal, as radial modes are integrated to find the convergence; here we wish to characterize this reduction in signal. We find that after a simple model of foreground removal, the cross-correlation signal is reduced by |$\sim$| 50–70  per cent; we present the angular and redshift dependence of the effect, which is a weak function of these variables. We then calculate S/N of |$\kappa$| HI detection, including cases with cut sky observations, and noise from radio and lensing measurements. We present Fisher forecasts based on the resulting two-point functions; these forecasts show that by measuring |$\kappa \Delta {T}_\mathrm{HI}$| correlation functions in a sufficient number of redshift bins, constraints on cosmology and HI bias will be possible. [ABSTRACT FROM AUTHOR]

Potential contamination from low/intermediate-redshift galaxies, such as objects with a prominent Balmer break, affects the photometric selection of high-redshift galaxies through identification of a Lyman break. Traditionally, contamination is estimated from spectroscopic follow-up and/or simulations. Here, we introduce a novel approach to estimating contamination for Lyman-break galaxy (LBG) samples based on measuring spatial correlation with the parent population of lower redshift interlopers. We propose two conceptual approaches applicable to different survey strategies: a single large contiguous field and a survey consisting of multiple independent lines of sight. For a large single field, we compute the cross-correlation function between galaxies at redshift |$z \sim 6$| and intermediate-redshift galaxies at |$z \sim 1.3$|⁠. We apply the method to the CANDELS GOODS-S and XDF surveys and compare the measurement with simulated mock observations, finding that the contamination level in both cases is not measurable and lies below 5.5 per cent (at 90 per cent confidence). For random-pointing multiple field surveys, we measure instead the number count correlation between high-redshift galaxies and interlopers, as a two-point correlation analysis is not generally feasible. We show an application to the LBG samples at redshift |$z \sim 8$| and the possible interloper population at |$z \sim 2$| in the Brightest of Reionizing Galaxies (BoRG) survey. By comparing the Pearson correlation coefficient with the result from Monte Carlo simulations, we estimate a contamination fraction of |$62^{+13}_{-39} \, \mathrm{ per}\, \mathrm{ cent}$|⁠ , consistent with previous estimates in the literature. These results validate the proposed approach and demonstrate its utility as an independent check of contamination in photometrically selected samples of high-redshift galaxies. [ABSTRACT FROM AUTHOR]

The measurement of the abundance of galaxy clusters in the Universe is a sensitive probe of cosmology, which depends on both the expansion history of the Universe and the growth of structure. Density fluctuations across the finite survey volume add noise to this measurement, this is often referred to as super-sample covariance (SSC). For an unbinned cluster analysis, such noise has not been included in the cluster likelihood, since the effect of SSC was small compared to the Poisson shot-noise for samples of a few hundred clusters. For upcoming large cluster surveys such as the Rubin LSST, which will deliver catalogues of tens of thousands of clusters, this effect will no longer be negligible. In this paper, we propose a new hybrid likelihood based on the Gauss-Poisson Compound model (GPC), by using infinitesimal mass bins and standard redshift bins. This likelihood has the advantages of an unbinned Poisson likelihood while successfully incorporating the effects of SSC. Using a simulated dark matter halo catalogue, we find that the hybrid likelihood, accounting for both Poisson noise and SSC, increases the dispersion of the parameter posteriors by 20 per cent when using 100 000 clusters compared to the standard unbinned likelihood, based on Poisson statistics only. [ABSTRACT FROM AUTHOR]

We examine deep optical images of edge-on galaxies selected from the Sloan Digital Sky Survey (SDSS) Stripe 82. The entire sample consists of over 800 genuine edge-on galaxies with spectroscopic redshifts out to |$z\sim 0.2$|⁠. To discern the faintest details around the galaxies, we use three different data sources with a photometric depth of down to 30 mag arcsec |$^{-2}$| in the r band: SDSS Stripe 82, Hyper Suprime-Cam Strategic Program, and DESI Legacy Imaging Surveys. Our analysis of the deep images reveals a variety of low surface brightness features. 49 galaxies exhibit prominent tidal structures, including tidal tails, stellar streams, bridges, and diffuse shells. Additionally, 56 galaxies demonstrate peculiar structural features such as lopsided discs, faint warps, and dim polar rings. Overall, we detect low surface brightness structures in 94 galaxies out of 838, accounting for 11  per cent of the sample. Notably, the fraction of tidal structures is only 5.8  per cent, which is significantly lower than that obtained in modern cosmological simulations and observations. Previous studies have shown that strongly interacting galaxies have stellar discs about 1.5–2 times thicker than those without apparent interactions. In an analysis where tidal features are carefully masked for precise disc axis ratio measurements, we show that discs of galaxies with tidal features are 1.33 times thicker, on average, than control galaxies that do not have visible tidal features. Furthermore, we find that edge-on galaxies with tidal structures tend to have a higher fraction of oval and boxy discs than galaxies without tidal features. [ABSTRACT FROM AUTHOR]

The size and complexity reached by the large sky spectroscopic surveys require efficient, accurate, and flexible automated tools for data analysis and science exploitation. We present the Galaxy Spectra Network/GaSNet-II, a supervised multinetwork deep learning tool for spectra classification and redshift prediction. GaSNet-II can be trained to identify a customized number of classes and optimize the redshift predictions. Redshift errors are determined via an ensemble/pseudo-Monte Carlo test obtained by randomizing the weights of the network-of-networks structure. As a demonstration of the capability of GaSNet-II, we use 260k Sloan Digital Sky Survey spectra from Data Release 16, separated into 13 classes including 140k galactic, and 120k extragalactic objects. GaSNet-II achieves 92.4 per cent average classification accuracy over the 13 classes and mean redshift errors of approximately 0.23 per cent for galaxies and 2.1 per cent for quasars. We further train/test the pipeline on a sample of 200k 4MOST (4-metre Multi-Object Spectroscopic Telescope) mock spectra and 21k publicly released DESI (Dark Energy Spectroscopic Instrument) spectra. On 4MOST mock data, we reach 93.4 per cent accuracy in 10-class classification and mean redshift error of 0.55 per cent for galaxies and 0.3 per cent for active galactic nuclei. On DESI data, we reach 96 per cent accuracy in (star/galaxy/quasar only) classification and mean redshift error of 2.8 per cent for galaxies and 4.8 per cent for quasars, despite the small sample size available. GaSNet-II can process ∼40k spectra in less than one minute, on a normal Desktop GPU. This makes the pipeline particularly suitable for real-time analyses and feedback loops for optimization of Stage-IV survey observations. [ABSTRACT FROM AUTHOR]